Dark matter (DM) is currently searched for with a variety of detection strategies. Accelerator searches are particularly promising, but even if weakly interacting massive particles are found at the Large Hadron Collider (LHC), it will be difficult to prove that they constitute the bulk of the DM in the Universe ${\Omega }_{\mathrm{DM}}$. We show that a significantly better reconstruction of the DM properties can be obtained with a combined analysis of LHC and direct detection data, by making a simple Ansatz on the weakly interacting massive particles local density ${\rho }_{{\tilde{\chi }}_1^0}$, i.e., by assuming that the local density scales with the cosmological relic abundance, $({\rho }_{{\tilde{\chi }}_1^0}/{\rho }_{\mathrm{DM}})=({\Omega }_{{\tilde{\chi }}_1^0}/{\Omega }_{\mathrm{DM}})$. We demonstrate this method in an explicit example in the context of a 24-parameter supersymmetric model, with a neutralino lightest supersymmetric particle in the stau coannihilation region. Our results show that future ton-scale direct detection experiments will allow to break degeneracies in the supersymmetric parameter space and achieve a significantly better reconstruction of the neutralino composition and its relic density than with LHC data alone.

Explicit applications of factorization theorems for processes at hadron colliders near the hadronic end point have largely focused on simple final states with either no jets (e.g., Drell-Yan) or one inclusive jet (e.g., deep-inelastic scattering and prompt photon production). Factorization for the former type of process gives rise to a soft function that depends on timelike momenta, whereas the soft function for the latter type depends on null momenta. We derive in soft-collinear effective theory a factorization theorem that allows for an arbitrary number of jets, where the jets are defined with respect to a jet algorithm, together with any number of nonstrongly interacting particles. We find the soft function in general depends on the null components of the soft momenta inside the jets and on a timelike component of the soft momentum outside of the jets. This generalizes and interpolates between the soft functions for the cases of no jets and one inclusive jet. We verify consistency of our factorization theorem to $\mathcal{O}({\alpha }_s)$ for any number of jets. While in this paper we demonstrate consistency only near the hadronic end point, we keep the kinematics general enough (in particular allowing for nonzero boost) to allow for an extension to partonic threshold resummation away from the hadronic end point.

A constant antisymmetric 2-tensor can arise in general relativity with spontaneous symmetry breaking or in field theories formulated in a noncommutative space-time. In this work, the one-loop contribution of a nonstandard $WW\gamma$ vertex on the flavor violating quark transition $q_i\to q_j\gamma$ is studied in the context of the electroweak Yang-Mills sector extended with a Lorentz-violating constant 2-tensor. An exact analytical expression for the on-shell case is presented. It is found that the loop amplitude is gauge independent, electromagnetic gauge invariant, and free of ultraviolet divergences. The dipolar contribution to the $b\to s\gamma$ transition together with the experimental data on the $B\to X_s\gamma$ decay is used to derive the constraint ${\Lambda }_{\mathrm{LV}}>1.96\mathrm{TeV}$ on the Lorentz-violating scale.

The flavor democracy hypothesis predicts the existence of the fourth standard model family. Because of the high masses of the fourth family quarks, their anomalous decays could be dominant if certain criteria are met. This will drastically change the search strategy at hadron colliders. We show that the fourth standard model family down quarks with masses up to 400–450 GeV can be observed (or excluded) via anomalous decays by Tevatron.

Using a sample of $471\times {10}^6$ $B\overline{B}$ events collected with the BABAR detector, we study the sum of seven exclusive final states $B\to X_{s(d)}\gamma$, where $X_{s(d)}$ is a strange (nonstrange) hadronic system with a mass of up to $2.0\mathrm{GeV}/c^2$. After correcting for unobserved decay modes, we obtain a branching fraction for $b\to d\gamma$ of $(9.2\pm 2.0(\mathrm{stat})\pm 2.3(\mathrm{syst}))\times {10}^{-6}$ in this mass range, and a branching fraction for $b\to s\gamma$ of $(23.0\pm 0.8(\mathrm{stat})\pm 3.0(\mathrm{syst}))\times {10}^{-5}$ in the same mass range. We find $\frac{\mathcal{B}(b\to d\gamma )}{\mathcal{B}(b\to s\gamma )}=0.040\pm 0.009(\mathrm{stat})\pm 0.010(\mathrm{syst})$, from which we determine $|V_{td}/V_{ts}|=0.199\pm 0.022(\mathrm{stat})\pm 0.024(\mathrm{syst})\pm 0.002(\mathrm{th})$.

The purpose of this article is to extend the light-cone worldsheet lattice description of string theory to include the Neveu-Schwarz model. We model each component of the fermionic worldsheet field by a critical Ising model. We show that a simple choice of boundary conditions for the Ising variables leads to the half-integer modes required by the model. We identify the $G$-parity operation within the Ising model and formulate the procedure for projecting onto the even $G$-parity sector. We construct the lattice version of the three open string vertex, with the necessary operator insertion at the interaction point. We sketch a formalism for summing planar open string multiloop amplitudes, and we discuss prospects for numerically summing them. If successful, the methods described here could provide an alternative to lattice gauge theory for computations in large $N$ QCD.

We explore the consequences of the mass generation due to the Higgs field in strong gravity astrophysical environments. The vacuum expectation value of the Higgs field is predicted to depend on the curvature of spacetime, potentially giving rise to peculiar spectroscopic shifts, named hereafter “Higgs shifts.” Higgs shifts could be searched through dedicated multiwavelength and multispecies surveys with high spatial and spectral resolution near strong gravity sources such as Sagittarius ${\mathrm{A}}^{*}$ or broad searches for signals due to primordial black holes. The possible absence of Higgs shifts in these surveys should provide limits to the coupling between the Higgs particle and the curvature of spacetime, a topic of interest for a recently proposed Higgs-driven inflationary model. We discuss some conceptual issues regarding the coexistence between the Higgs mechanism and gravity, especially for their different handling of fundamental and composite particles.

We show that inflationary cosmology may be used to test the statistical predictions of quantum theory at very short distances and at very early times. Hidden-variables theories, such as the pilot-wave theory of de Broglie and Bohm, allow the existence of vacuum states with nonstandard field fluctuations (“quantum nonequilibrium”). We show that inflationary expansion can transfer microscopic nonequilibrium to macroscopic scales, resulting in anomalous power spectra for the cosmic microwave background. The conclusions depend only weakly on the details of the de Broglie-Bohm dynamics. We discuss, in particular, the nonequilibrium breaking of scale invariance for the primordial (scalar) power spectrum. We also show how nonequilibrium can generate primordial perturbations with nonrandom phases and intermode correlations (primordial non-Gaussianity). We address the possibility of a low-power anomaly at large angular scales, and show how it might arise from a nonequilibrium suppression of quantum noise. Recent observations are used to set an approximate bound on violations of quantum theory in the early Universe.

We propose a novel mechanism for dark matter to explain the observed annual modulation signal at DAMA/LIBRA which avoids existing constraints from every other dark matter direct detection experiment including CRESST, CDMS, and XENON10. The dark matter consists of at least two light states with mass $\sim \mathrm{\text{few}}\mathrm{GeV}$ and splittings $\sim 5\mathrm{keV}$. It is natural for the heavier states to be cosmologically long-lived and to make up an $\mathcal{O}(1)$ fraction of the dark matter. Direct detection rates are dominated by the exothermic reactions in which an excited dark matter state downscatters off of a nucleus, becoming a lower energy state. In contrast to (endothermic) inelastic dark matter, the most sensitive experiments for exothermic dark matter are those with light nuclei and low threshold energies. Interestingly, this model can also naturally account for the observed low-energy events at CoGeNT. The only significant constraint on the model arises from the DAMA/LIBRA unmodulated spectrum but it can be tested in the near future by a low-threshold analysis of CDMS-Si and possibly other experiments including CRESST, COUPP, and XENON100.

We show that scalar, 0-form, Galileon actions—models whose field equations contain only second derivatives—can be generalized to arbitrary even $p$-forms. More generally, they need not even depend on a single form, but may involve mixed $p$ combinations, including equal $p$ multiplets, where odd $p$ fields are also permitted: We construct, for given dimension $D$, general actions depending on scalars, vectors, and higher $p$-form field strengths, whose field equations are of exactly second derivative order. We also discuss and illustrate their curved-space generalizations, especially the delicate nonminimal couplings required to maintain this order. Concrete examples of pure and mixed actions, field equations, and their curved-space extensions are presented.

Technidilaton, a pseudo–Nambu-Goldstone boson of scale symmetry, was predicted long ago in the scale-invariant/walking/conformal technicolor (SWC-TC) as a remnant of the (approximate) scale symmetry associated with the conformal fixed point, based on the conformal gauge dynamics of ladder Schwinger-Dyson (SD) equation with nonrunning coupling. We study the technidilaton as a flavor-singlet bound state of technifermions by including the technigluon condensate (tGC) effect into the previous (bottom-up) holographic approach to the SWC-TC, a deformation of the holographic QCD with ${\gamma }_m\simeq 0$ by large anomalous dimension ${\gamma }_m\simeq 1$. With including a bulk scalar field corresponding to the gluon condensate, we first improve the operator product expansion of the current correlators so as to reproduce gluonic $1/Q^4$ term both in QCD and SWC-TC. We find in QCD about 10% (negative) contribution of gluon condensate to the $\rho$ meson mass. We also calculate the oblique electroweak $S$-parameter in the presence of the effect of the tGC and find that for the fixed value of $S$ the tGC effects dramatically reduce the flavor-singlet scalar (technidilaton) mass $M_{\mathrm{TD}}$ (in the unit of $F_{\pi }$), while the vector and axial-vector masses $M_{\rho }$ and $M_{a_1}$ are rather insensitive to the tGC, where $F_{\pi }$ is the decay constant of the technipion. If we use the range of values of tGC implied by the ladder SD analysis of the nonperturbative scale anomaly in the large $N_f$ QCD near the conformal window, the phenomenological constraint $S\simeq 0.1$ predicts the technidilaton mass $M_{\mathrm{TD}}\sim 600\mathrm{GeV}$ which is within reach of LHC discovery.

We demonstrate that in effective theories arising from a class of $\mathcal{N}=1$ fluxless compactifications of M theory on a $G_2$ manifold with low-energy supersymmetry, $CP$-violating phases do not appear in the soft-breaking Lagrangian except via the Yukawas appearing in the trilinear parameters. Such a mechanism may be present in other string compactifications as well; we describe properties sufficient for this to occur. $CP$ violation is generated via the Yukawas since the soft trilinear matrices are generically not proportional to the Yukawa matrices. Within the framework considered, the estimated theoretical upper bounds for electric dipole moments of the electron, the neutron, and mercury are all within the current experimental limits and could be probed in the near future.

We investigate the role of the isoscalar-vector interaction and the dynamics of the Polyakov loop on inhomogeneous phases in the phase diagram of the two-flavor Nambu-Jona–Lasinio model. Thereby we concentrate on inhomogeneous phases with a one-dimensional modulation, explicitly domain-wall solitons and, for comparison, the chiral spiral. While the inclusion of the Polyakov loop merely leads to quantitative changes compared to the original Nambu-Jona–Lasinio model, the inclusion of a repulsive vector-channel interaction has significant qualitative effects: Whereas for homogeneous phases the first-order phase transition gets weakened and eventually turns into a second-order transition or a crossover, the domain of inhomogeneous phases is less affected. In particular the location of the Lifshitz point in terms of temperature and density is not modified. Consequently, the critical point disappears from the phase diagram and only a Lifshitz point (showing a different critical behavior) remains. In particular, susceptibilities remain finite.

We study the effects of holographic renormalization on an AdS/QCD inspired description of dynamical electroweak symmetry breaking. Our model is a 5D slice of ${\mathrm{AdS}}_5$ geometry containing a bulk scalar and $SU(2)\times SU(2)$ gauge fields. The scalar field obtains a vacuum expectation value (VEV) which represents a condensate that triggers electroweak symmetry breaking. Fermion fields are constrained to live on the UV brane and do not propagate in the bulk. The two-point functions are holographically renormalized through the addition of boundary counterterms. Measurable quantities are then expressed in terms of well-defined physical parameters, free from any spurious dependence on the UV cutoff. A complete study of the precision parameters is carried out and bounds on physical quantities derived. The large-$N$ scaling of results is discussed.

We report on the measurement of two-pion correlation functions from $pp$ collisions at $\sqrt{s}=900\mathrm{GeV}$ performed by the ALICE experiment at the Large Hadron Collider. Our analysis shows an increase of the Hanbury Brown–Twiss radius with increasing event multiplicity, in line with other measurements done in particle- and nuclear collisions. Conversely, the strong decrease of the radius with increasing transverse momentum, as observed at the Relativistic Heavy Ion Collider and at Tevatron, is not manifest in our data.

Previously developed analytic models for the evolution of cosmic string and monopole networks are applied to networks of monopoles attached to two or more strings; the former case is usually known as cosmic necklaces. These networks are a common consequence of models with extra dimensions such as brane inflation. Our quantitative analysis agrees with (and extends) previous simpler estimates, but we will also highlight some differences. A linear scaling solution is usually the attractor solution for both the radiation and matter-dominated epochs, but other scaling laws can also exist, depending on the universe’s expansion rate and the network’s energy loss mechanisms.

We show that the one-loop effective action at finite temperature for a scalar field with quartic interaction has the same renormalized expression as at zero temperature if written in terms of a certain classical field ${\varphi }_c$, and if we trade free propagators at zero temperature for their finite-temperature counterparts. The result follows if we write the partition function as an integral over field eigenstates (boundary fields) of the density matrix element in the functional Schrödinger field representation, and perform a semiclassical expansion in two steps: first, we integrate around the saddle point for fixed boundary fields, which is the classical field ${\varphi }_c$, a functional of the boundary fields; then, we perform a saddle-point integration over the boundary fields, whose correlations characterize the thermal properties of the system. This procedure provides a dimensionally reduced effective theory for the thermal system. We calculate the two-point correlation as an example.

We identify universal quasiconformal (walking) behavior in non-Abelian gauge field theories based on the mass-dependent all-order $\beta$ function introduced in [D. D. Dietrich, Phys. Rev. D 80, 065032 (2009)]. We find different types of walking behavior in the presence of (partially) massive species. We employ our findings to the construction of candidate theories for dynamical electroweak symmetry breaking by walking technicolor.

Using the relativistic Hartree-Fock approximation, we calculate the rates of atomic ionization by absorption of axions of the energies up to 100 keV and for an arbitrary value of the axion mass. We present numerical results for atoms used in the low radioactive background searches of dark matter (e.g., Ar, Ge, and Xe), as well as an analytical formula which fits numerical calculations for the absorption cross sections and can be applied to other atoms, molecules, and condensed matter systems. Using the cross sections for the axio-electric effect, we derive the counting rates induced by solar axions and set limits on the axion coupling constants.

The effects of $(\mathrm{\text{curvature}}{)}^2$- and $(\mathrm{\text{torsion}}{)}^2$-terms in the Einstein-Hilbert-Chern-Simons Lagrangian are investigated. The purposes are two-fold: (i) to show the efficacy of an orthogonal basis of degree-of-freedom projection operators recently proposed and to ascertain its adequacy for obtaining propagators of general parity-breaking gravity models in three dimensions; (ii) to analyze the role of the topological Chern-Simons term for the unitarity and the particle spectrum of the model squared-curvature terms in connection with dynamical torsion. Our conclusion is that the Chern-Simons term does not influence the unitarity conditions imposed on the parameters of the Lagrangian but significantly modifies the particle spectrum.